C-arm machines are widely used, for example, in medical technology. In the case of such machines, a diagnostic or treatment device is fastened to a C-shaped main body. Because its shape, the C-arm, and with it the diagnostic or treatment device, may be moved orbitally around a point on a patient that is to be examined or treated. Thus, various angular positions between the patient and the diagnostic or treatment device may be achieved without the patient having to be repositioned.
Especially popular as diagnostic devices are x-ray imaging devices, in which an x-ray source is attached to one end of the C-arm and an x-ray detector or image intensifier is attached to the opposite end. The C-arm is mounted on rollers and on these may be pivoted about an orbital axis. Such a C-arm x-ray machine is described by way of example in DE 10 2004 011 460 A1.
FIG. 1 depicts part of a C-arm 1 of an x-ray imaging device according to the prior art. The C-arm 1 includes extruded aluminum. As may be seen from the drawing, the main body 2 of the C-arm 1 is formed as one piece and has in cross section the shape of a double H. The running rollers 7, which are mounted on running wires 8 made of steel that are arranged in grooves of the “ears” of the main body 2, may likewise be seen. On the running rollers 7, the C-arm 1 may perform an orbital movement about an isocenter.
Due to the position of the running wires 8, with large C-arms 8 and/or with heavy loads on the C-arm 1 the “ears” of the double-H profile may flex. This results in a relatively great, undesired displacement of the imaging components that are fastened to the C-arm. Furthermore, the decay time for the resultant oscillation in braking and accelerating operations is increased by the mutual excitement of the “ears”. However, for applications such as “Needle Guidance” or 3D image recording, it is important that there is as little displacement as possible. It is likewise important for 3D image recording to have a decay time that is as small as possible, since this influences the waiting time in the end positions during the application, and consequently the overall application time.
One possible way of preventing this is not to use “ears” and to allow the running rollers to run directly on the corners of the rectangular profile. Such an arrangement is disclosed in German patent application DE 10 2010 021 657 A1.